Cold rolling mill



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United States Patent 3,503,241 COLD ROLLING MILL Walter vom Dorp, Fritz Zeunert, and Horst Stinnertz, Rheydt, Germany, assignors to Mannesmann-Meer Aktiengesellschaft, Monchen-Gladbach, Germany, a corporation of Germany Filed June 6, 1966, Ser. No. 555,420 Claims priority, application Germany, Sept. 23, 1965,

66,738; Nov. 16, 1965, M 67,291

Int. Cl. B21d 7/02 US. Cl. 72214 1 Claim ABSTRACT OF THE DISCLOSURE A pilger cold rolling mill with an oscillating frame has balancing means therefor and shrunk-mounted roll groove rings the developed length of which is from 1.5 to 2.5 times that of conventional roll jaws of the same groove diameter.

The invention relates to cold rolling mills, and relates more particularly to cold rolling mills of the pilger or step-back type. Still more particularly, the invention relates to such cold rolling mills of the step-back type, that have an oscillating rolling frame including acceleration power and mass frame balancing means. Reference is had to German Patent No. 962,062 and to German Patent No. 1,064,461 wherein at the crank shaft throws there are mounted counterbalancing weights, the mass forces of which correspond to the occurring mass forces of the rolling frame, respectively correspond to the balancing mass for the mass acceleration eifort. With an arrangement of the aforesaid features, a considerable increase in the output could be achieved.

Yet, still more particularly, the invention relates to cold rolling mills of the step-back type, which are particularly suitable for that type rolling of tubes.

In cold rolling mills of the step-back type, for use in connection with the rolling of tubes, the working groove generally is disposed in the so-called roll jaw, which is an inset piece that is held exchangeably by means of suitable mounting means in a cutout; it is known to provide rolls with two or more working grooves, in accordance with German Patent No. 1,067,758, in order to obtain thereby an additional increase in production, particularly as, due to the power and mass force balancing means system, there will result a substantial lowering of the stress applied to the transmission that is disposed between the driving motor and the crank shaft; this, in turn, permits a substantial increase in the available rotational speed, with resultant production increase.

Rolling arrangements with two or more working grooves side by side, however, demand means for the clamping, turning and feeding of the rolled material in multiple fashion; hence the effort required for systems with two or more adjoining working grooves is considerable, and requires substantial expenditures, aside from the difliculties to coordinate the diverse movements and parts in the system.

It is accordingly among the principal objects of the invention, to provide a cold rolling mill of the step-back type wtih but a single working groove which, nonetheless, renders possible the output that is comparable to the output of a system with two or more working grooves arranged side by side. This is accomplished by providing the single roll groove with a developed work length that is from about 1.5 to about 2.5 times that of conventional roll jaws, yet without roll diameter increase.

It is a further object of the invention to provide such a mill in which the tools, namely the working rolls, are so mounted that the maintenance is simple, and the principles Patented Mar. 31, 1970 of which may be used with multiple working grooves without any appreciable change in construction.

The instant invention provides for a cold rolling mill of the step-back type, with oscillating rolling frame means and power and mass force balancing means, a rotatable carrier shaft, at least one roll groove ring being exchangeably mounted on the carrier shaft and having an external circumference defining an extended working groove length surpassing 220; this extension of the working groove length corresponds to an extension of from about 1.5 to about 2.5 times the lengths of the roll jaws heretofore used.

It is still another object of the invention to provide a cold rolling mill of the aforesaid type in which each roll groove ring is shrunk on the carrier shaft without use of any slot and key, and is fixed in its position in peripheral direction relative to the shaft by position determining means which include a portion near one lateral face of the roll groove ring, a portion of a radially extending member formed on the shaft, and a wedge member that extends between these portions.

In systems now in use, in contrast thereto, the rolls are provided with inset groove jaws; and where the working groove length is doubled, there must also be doubled the roll diameter, as a result of which the weight of the rolling frames increases considerably furthermore, the roll jaws thus would assume prohibitively large dimensions, and lastly the roll pressure would increase disadvantageously correspondingly.

It is yet a further object of the invention to avoid the aforesaid and other drawbacks of the prior art.

Rolling mill constructions have previously been made that included so-called roll groove rings. Such a roll groove ring is formed of a ring made of suitable material, which is positioned on the roll shaft either by means of slot and key, or by means of a square fit. Into this ring there has been worked the necessary groove out, which corresponds in its lengths to the set-in roll jaws, with the advantage, however, of a smaller roll diameter.

To decrease the roll diameter and yet not to decrease the yield, has been the aim of these constructions.

The instant invention provides for a considerable lengthening of the working groove length and yet maintaining the same ring roll diameter as had been done for rolls with jaw grooves. In this manner, the stroke of the oscillating rolling frame is increased without increasing the Work rotations per minute, and thus a corresponding yield increase is achieved.

if it were tried to increase the working stroke length of the prior art considerably, either to increase the yield, or to decrease the reaction pressure of the arbor without, however, reducing the working revolutions per minute, for instance increasing that length from about 1.5 to about 2.5 times, then the weight of the rolling frames would be increased approximately in accordance with the square of the lengthening of the working stroke, thus from about 2.25 to about 6.5 times. With a cold rolling mill of the prior art with a thus increased working groove length, however, the acceleration efiorts during operation and the mass forces at the crank mechanism and at the machine frame and foundation would be so large, that operation could not be accomplished without power and mass force balancing means.

Where, for instance, it is desired to reduce the diameter from 4 /2 in. to 2 in., the working groove length would need to be increased from 40 in. to 45 in., if the reaction forces and the taper of the arbor are to be held within manageable magnitudes.

It is accordingly among the still further objects of the invention to utilize primarily the considerable increase in the working groove length for the purpose to increase the output and to decrease the forces applied to the arbor.

This may be accomplished on one hand with the aid of the aforesaid roll groove rings, and on the other hand with the aid of the aforesaid power and mass force balancing system.

It is, however, known from practical experience that where, for instance, a triple cold rolling mill of the stepback type for 4 /2 in. is provided with roll groove rings with an overall stroke length of the rolling frame of about 1300 mm. (SO -52 in.), the mill can operate with a stroke frequency of 120 per minute only if it is provided with an output and mass force balancing system. Without such a balancing system, the frequency of the strokes could not be increased beyond about 80 per minute.

The instant invention provides for power and mass force balancing and thereby for a reduction in the stress of the movable parts including the transmission. Thus the combination of the aforementioned and later described means employed in accordance with the invention results in a considerably longer working groove length and, coupled with power and mass force balancing, provides for a machine which in its performance matches that of a machine of the prior art that had two or more working grooves side by side. The high stresses to which the working grooves are subjected, affected, of course, in the prior art adversely the life of these roll grooves. In accordance with the instant invention, however, this drawback is compensated by the great ease of mounting and dismounting of the parts for repair and for exchange.

In machines of the prior art, the roll rings were positively connected with the carrier shaft by means of a key and slot arrangement; at multiple machines of this type, the length of the key and slot were so extended that spacer rings that were disposed between the multiple roll rings were held by the same key and slot as the roll rings themselves. As this means of attachment was, however, not entirely satisfactory, the roll rings have additionally been shrunk onto the respective shafts.

Attempts have furthermore been made to utilize wellknown heating means to loosen and to remove the ring rolls off the shafts, for the purpose of repair of the worn roll grooves. This, however, met with considerable difficulty, as the heating caused the occurrence of maximum stresses in the base corners of the slots for the keys, which led partially to fissures and partially, owing to the shrinking pressure against the relatively small key surfaces, even led to fusion; hence dismounting using the previous heating means and heating methods could be accomplished only with the aid of special dismounting mechanisms; or by at least the partial destruction of some of the parts. The aforesaid occurrences have an adverse effect on the economy of the plants of the prior art, caused mainly by the necessity to keep on hand a large amount of roll groove rings. Furthermore, the aforesaid dismounting required a great deal of time.

It is still a further object of the invention to provide a cold rolling mill of the type described, wherein no slot is formed in the shaft surface.

It is still another object of the invention to provide such a cold rolling mill, inwhich the roll groove rings are shrunk onto the shaft, without any key and slot arrangement such as had been used by the prior art.

It is yet a further object of the invention to provide such a cold rolling mill wherein the carrier shaft has a radially extending member, for instance a flange, that has a number of, namely one or more axial grooves. The roll groove ring has at one of its end faces the same number of grooves but which are radial (instead of axial). A prismatic wedge member extends between each axial and radial groove, to position the roll ring peripherally relative to the carrier shaft. Where multiple machines are used, that provide for spacer rings between the adjoining roll rings, the spacer rings will also have corresponding radial grooves in the faces, so that with the aid of prismatic wedge members, the peripheral position of the roll rings and of the spacer rings relative to the carrier shaft will be fixed; furthermore, these groove-wedgegroove connections provide for additional holding be tween the parts, so that now each roll groove ring which is shrunk onto the carrier shaft and is positioned in the aforesaid groove-wedge-groove manner is positively connected and positioned for rotation with the carrier shaft.

This, however, has the further advantage that the mounting and dismounting is much facilitated.

It is a still further object of the invention to provide for heating means, for instance for inductive heating means, and the shaft and heating means are so positionable relative to each other, that the heating means will heat the rings sufficiently for the subsequent removal of the rings off the shaft.

It is yet another object of the invention to provide heating means, for instance inductive heating means for such a carrier shaft and roll groove rings and perhaps also spacer rings thereon, that permit the covering by the heating means of all the rings simultaneously and, upon ver tical suspension of the carrier shaft, the easy withdrawing of the rings off the carrier shaft, after the rings have been heated by the heating means sufficiently for such drawing off; this has the advantage that this kind of withdrawal is made possible without need for any special mechanical ring removing device.

The instant invention provides thus for cold rolling mills of the step-back type which, when using only one roll groove ring, permit large production; yet, permit the side-by-side arrangement of several roll groove rings rendering possible great economies in initial tool costs and in erection costs, and making possible the economic production of first class end products.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description, taken in connection with the accompanying drawings, in which:

FIG. 1 is a schematic vertical sectional view of a cold rolling mill of the step-back type with frame and motor and balancing means;

FIG. 1b is a large scale schematic view, partly in section, of a roll groove ring and taper of the arbor, showing the circumferential groove of the roll groove ring;

FIG. 2 is a sectional view of a carrier shaft having a single roll groove ring mounted thereon;

FIG. 3 is a sectional view, similar to FIG. 2, but showing a carrier shaft with three roll groove rings mounted thereon, with two spacer rings each between two roll groove rings; and

FIG. 4 is a schematic view, partly in section, showing a carrier shaft suspended vertically on which there are mounted three roll groove rings, and inductive heating means for heating the rings for their subsequent removal off the shaft.

In carrying the invention into effect in the embodiments which have been selected for illustration in the accompanying drawings and for description in this specification, and referring now particularly to FIG. 1, there is provided a cold rolling mill of the step-back type that includes mass balancing means 1, a motor 2, an oscillating rolling frame 3, and a roll groove ring 4. The rack which is needed for turning the roll groove rings has been omitted from FIG. 1, for the sake of clarity and simplicity.

The circumferential form of the roll groove rings 4 exhibited in FIG. 1b, shows the stroke x that is rendered possible by this design, and furthermore also the tapered shape of the bloom to be formed on the rolling mill is shown in FIG. 1b.

The reduction work, as is well known, commences with the control stroke a for the feed; then there follows the reduction groove 17; thereafter there follows the smoothing groove c, and finally the control stroke d for the turning of the bloom. The distance e is the entire work length, while x indicates the entire stroke. The distance e corresponds to the developed work length of the roll groove ring 4, which length is about from 1.5 to about 2.5 ,times the developed work length of conventional roll jaws of the same groove diameter.

As shown in FIGS. 1-4, the roll groove rings 4 are shrunk onto the rotatable carrier shaft 7 for positive rotational connection, yet without use of any shaft key.

The carrier 7 has a radially extending member, such as a flange 8 which has near its circumference in axial direction prismatic axial grooves 9. The amount of grooves 9 per flange 8 may vary with the need.

The roll groove rings 4, on the other hand, have on their faces the same amount of grooves 10 which, however, extend in radial direction (see FIG. 2).

Where multiple roll groove rings are used (see FIG. 3), there are provided spacer rings 11 between the roll groove rings 4. The spacer rings 11 also have in their faces the same amount of radially directed grooves 12.

By inserting prismatic wedge members 13 into these grooves, the roll groove rings 4 are fixed peripherally relative to the carrier shaft and its pinion; where multiple roll groove rings are used (FIG. 3), they are coordinated in this manner in their development. The wedge members 13 are secured from falling oil by means of rings 14.

In FIG. 4 there is shown a means for a time-saving and easy dismounting of the rings off the carrier shaft. Inductive heating means 15 are shown, though only schematically, which in the case of multiple roll groove rings on the carrier shaft may cover all the roll groove rings; where only single roll groove rings are used, the heating means may be so arranged that the parts thereof which do not cover any roll groove ring may selectively be disconnected electrically.

For dismounting, the carrier shaft, after the pinion has been removed, will be suspended vertically, and then the heating means 15 will apply heat to the rings, of sufiicient quantity so that the rings may thereafter be slid downwardly off the shaft, without need for any special mechanical ring removing device.

We wish it to be understood that we do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

References Cited UNITED STATES PATENTS 3,335,593 8/1967 Zeunert 72249 1,732,042 10/1929 Fox 29125 1,938,995 12/1933 Beynon 29-447 XR 2,192,808 3/1940 Van Der Bungelaar 72214 2,537,356 l/l951 Larsson 72-214 2,703,999 3/1955 Gille 72214 2,787,956 4/1957 Kirby et al. a- 29447 3,030,835 4/1962 Krause 72214 3,309,910 3/1967 Zeunert et al 72238 MILTON S. MEHR, Primary Examiner US. Cl. X.R. 29-125 

